Tuesday, August 20, 2013

Regulations for Crankcase & Relief Valve of Diesel Engines: Regulation Requrement Series

Regulation Requirement Series
"CRANKCASE AND CRANKCASE RELIEF VALVE"

2. DESIGN AND CONSTRUCTION OF ENGINES

2.1 CRANKCASE

  • The scantling of crankcase doors to be of sufficient strength, and the doors are to be securely fastened so that they will not be readily displaced by an explosion.
  • The ventilation of crankcases, or any other arrangement which may produce an inrush of air, is prohibited.
  • If provision is made for the forced extraction of gases from the crankcase (e.g. for detection of explosive mixtures), the vacuum in the crankcase is not to exceed: 2.5x10-4 MPa.
  • Where two or more engines are installed, their vent pipes and lubricating oil drain pipes are to be independent to avoid intercommunication between crankcases.Lubricating oil drain pipes from the engine sump to the drain tank are to be submerged in the latter at their outlet ends.
2.2 CRANKCASE RELIEF VALVE
  • Diesel engines of a cylinder diameter of 200 mm and above or a crankcase gross volume of 0.6 m3 and above are to be provided with crankcase explosion relief valves of a suitable type with sufficient relief area.
  • The relief valves are to be arranged or provided with suitable means to ensure that discharge is so directed as to minimize the possibility of injury to personnel.
  • The relief valves are to be of the spring-loaded type capable of quickly relieving the over pressure in the event of an internal explosion and closing immediately thereafter to prevent any inrush of air.
  • The valves are to be designed and constructed to open quickly at a pressure not greater than 0.2 bar above normal or 10-20% above normal and to close quickly and automatically in order to avoid an inrush of air in the crankcase.
  • They are to be of an approved type.
  • The valve covers are to be of metallic ductile material able to withstand the impact of the stops at the end of the lift.
  • The discharge from the valves is to be properly shielded in order to reduce the possible danger from emission of flame.

  • Valve Placement Criteria:

  • Engines of a cylinder diameter of 200 mm and above, but not exceeding 250 mm, are to have at least one valve near each end; however, for engines with more than 8 crankthrows, an additional valve is to be fitted near the middle of the engine. Engines of a cylinder diameter exceeding 250 mm, but not exceeding 300 mm, are to have at least one valve in way of each alternate crankthrow, with a minimum of two valves.Engines of a cylinder diameter exceeding 300 mm are to have at least one valve in way of each main crankthrow. Additional valves are to be fitted on separate spaces of the crankcase, such as gear or chain cases for camshaft or similar drives, when the gross volume of such spaces is 0,6 m3 or above.

  • Explosion Relief Valves:

  • Scavenge spaces in open connection to the cylinders are to be fitted with explosion relief valves.
  • The free area of each crankcase explosion relief valve is not to be less than 45 cm2. The aggregate free area of the valves fitted on an engine is not to be less than 115 cm2 per cubic metre of the crankcase gross volume.
  • Subject to the above provisions, each relief valve may be replaced by not more than two relief valves of smaller area, provided the free area of each valve is not less than 45 cm2.

Watch out for the next post on Regulation Requirements for...
Diesel Engine Machinery Requirements

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